Herein disclosed are embodiments pertaining to an apparatus and process for separating toner from a toner/carrier mixture, such as for example, waste toner containing carrier. The apparatus and process described herein operate much more efficiently to separate low density particles from larger, high density particles.
Reclaiming toner from electrophotographic machines is a highly desirable alternative to depositing toner in landfills or subjecting toner to incineration. Reclaim of field returned waste toner through addition into an extruder is a known process for some existing toners. A conventional manner of producing such toner is disclosed in Laing et al., U.S. Pat. No. 5,888,691, which is herein all incorporated by reference.
A problem that limits the efficiency of the reclaiming process, however, is that modern xerographic devices applies replenisher (toner plus some 5% to 40% fresh carrier) rather than only toner. Replenishers are used in order to keep the developer (carrier with up to 5% toner) in a steady-state aging condition. The equivalent amount of added fresh carrier leaves the developer through an overflow system and for some of these devices both waste toner and waste carrier are collected in the same waste bottle.
For example, some waste toners are estimated to include about 40% to 50% carrier by weight of the total waste toner weight. At such high carrier to toner ratios, the conventional carrier separation process through direct turboscreening, for example, screening over 44 microns, is no longer feasible as frequent screen blinding will occur. In blinding, the screen apertures may become clogged or covered by the heavier and larger carrier particles and thus become inefficient in operation or cease to operate properly altogether. As a result, such waste toners is not available for reclaim into regular toner processing.
Thus, there is a need for a more efficient separation process, and apparatus for performing such, to separate low density particles from a mixture of high and low density particles, including an apparatus and process for efficiently reclaiming waste toners, including those that have a high carrier content, to allow reclaim through regular toner processing.